In regard with an exercise for keeping or improving health or physical strength, that is, a fitness activity, a function of a heart or a lung may be improved by the amount of oxygen absorbed into a body. For example, Patent Documents 1 and 2 disclose a training machine having a configuration in which oxygen is supplied to a training person.
Further, as an oxygen supply device provided at a predetermined facility, there is known a configuration in which oxygen is supplied to users through a pipe provided in the facility. According to such a configuration, there is an advantage that an individual tank or an individual oxygen generator does not need to be provided for each user. This kind of oxygen supply device is disclosed in Patent Documents 3 and 4.    Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2003-265645    Patent Document 2: JP-A No. 2007-185457    Patent Document 3: JP-A No. 2001-327602    Patent Document 4: JP-A No. 2006-328931